Surface cleaning apparatus and method



April 21, 1959 J. w. MCAULEY ET AL SURFACE CLEANING APPARATUS AND METHOD2 Sheets-Sheet 1 Filed July 1, 1954 INVENTORS @wau? $221 ATTORNEYSIII-III vv amm April 21, 1959 'J. w. MCAULEY ET AL 2,883,310

SURFACE CLEANING APPARATUS AND METHOD Filed July 1, 1954 2 Sheets-Sheet2 INVENTORS fid ZML F/aala 29m A TTORNE YS plaster from'the fiat topsof'metal the surfacing of plate also remove layer 'to receive subsequentblanks to be surfaced.

tables, the 'and heretofore-cleaning of the tables has been done by:rotary wire brushes which acted inconjunction with water *dium;cavitation being the ellect "tion and collapse of solid material; andtationcan be used to disintegrate partielesofforeign. mat- United StatesPatent SURFACE CLEANING APPARATUS AND METHOD Application'lulylg1954,Serial No.'440,774 11 Claims. (Cl..134-1) 'The present inventionrelates'broadly towashing or cleaning, and more particularly to animproved method and apparatus for cleaning surfaces by high frequencyvibrations.

Although the invention is'not restricted to the cleaning of anyparticular article or type of surface, it is especially'well adapted tocarryout'the difficult job of removing tables employed in glass andwillbe'described in that connectionhere.

In'the regular commercial production of'plate glass,

"the unfinished glass "blanks are ordinarily bedded upon surfacingtables in a layer ofplaster of Paris-or the like 'which securely holdsthem in and-polishing thereof. After the 'glass'has been surfaced placeduring the grinding the blank is removed "from'the tables and it isnecessaryto the old plasterbedding and to apply afresh Because of thegood bond'between the plaster and the removal of the old plasterpresents a problem under pressure to remove the'plaster by an abradingaction upon the tables.

However, the abrading action-of area to be damp, dangerous andunsightly. Further deficiences also inherent insuch a cleaning procedureinvolve increased maintenance costs resulting from the necessity forfrequently adjusting the brushes as they '-wear down, and the replacingselves.

It is therefore a primary object of this inventionto provide a methodand device which will-clean fiat surfaced bodies in an expeditious andefficientmanner.

More the washing of and rapid maninvention contemplates to thecharacteristics of the sound waves. In this manner,'the sound waves willcreate cavitation in a liquid meof the alternate "forma- 'gas bubbles orcavities. lapse of the cavities creates an agitation of suflicientmagnitude to actually disintegrate particles of substantially wehavefound that thisvibratory agiter on the-surfaces to be may be easily andreadily phenomenon just described,

description when taken in ,each of the openings cleaned so that suchparticles removed therefrom.

present invention employs the to clean and remove plaster from surfacingtables by continuously passing such tables 'In a specific aspect, the

beneath vibration generating elements while maintaining a supply of asuitable energy conducting medium between said elements and the surfaceof the tables.

It is therefore another object of the invention to providea meanswhereby a plurality of vibration generating elements may be mountedabove the path of a conveying means so that the generating faces thereofwill completely traverse the surface of the conveying means as it passestherebeneath.

Another object of the invention is to provide a means whereby a thinfilm of a liquid transmitting medium may be confined to a very small andlocalized area over the surface being cleaned.

Further objects and advantages of the invention will became moreapparent during the course of the following connection with theaccompanying drawings.

In the drawings, wherein like numerals are employed to designate likeparts throughout the same:

Fig. 1 is a perspective view of one form of cleaning apparatusconstructed in accordance with the invention;

Fig. 2 is a vertical section taken substantially on line 2-2 of Fig. 1;

Fig. 3 is a partial :side elevation of an adjustment means for themounting of the vibration generating elements;

Fig. 4 is a sideview of a vibration generating element or transducerused in the cleaning apparatus of the inven- Fig. 5 is a partial planview of the apparatus of Fig. 1; and

Fig. 6 is a partial plan view of a modified arrangement of theinvention.

are secured upon the tops of the tables layer of plaster. This is donein Then after the glass has been surfaced by the grinding and polishingunits and removed from the tables in the unloading each end of the 14are vertical flange portions 17 which decross beam 12 adjacent the legsportions 16 and horizontal flange fine rectangular openings 18therebetween at the end of the beam. Slidablymounted for verticalmovement in 18 is an open frame type of clampmg bracket 19. Mountedwithin the clamping brackets 19 adjacent the opposite sides thereof arespecially formed channels 20 and 21 having grooves 22 therein andbridging the tables the channel 20 is secured to one side of each of thebrackets 19 by means of screws 23, and the channel 21 is slidablymounted along a finished slot 24 in the opposite side walls of thebrackets, being held in an adjusted position by an adjustment screw 24'.

The transducers 11, which are preferably of a magnetostrictive typehaving a laminated core 25 and electrical coil windings 26 (Fig. 4), aresupported by the channels 20 and 21 along nodal tabs 27 on the core 25,which tabs fit in the grooves 22 of the channels, as shown in Fig. 2.The nodal tabs 27 are located at a point of substantially zero vibrationof the transducer vibratory system so that a minimum of vibration energywill be imparted to the supporting structure, thus allowing a maximumamount of vibration energy to be expended upon the surface beingcleaned.

By virtue of the novel supporting means provided herein, the transducers11 may be easily removed from the supporting beam 12 to be repaired, orto be transferred to another cleaning table by merely loosening theadjustment screw 24 so as to allow the channel 21 to slide in the slot24 thus causing it to disengage one of the nodal tabs 27 on thetransducer core 25. After the channel 20 has been withdrawn from contactwith the transducer tabs 27 of any one of the transducers, it may beremoved from the beam by disconnecting the transducer power lead 28 andits associated plug 29 from the power supply housing 30 mounted on theupper side of the supporting cross beam 12.

As will best be seen in Fig. 5, the transducers 11 are spaced from eachother as at a and both the transducers and the support beam 12 areinitially arranged at an angle to the path of movement (designated bythe arrow x) of the tables 10. This spaced and angular arrangement notonly allows the transducers to vibrate without interference from eachother, but it also provides a means whereby the corner b of thetransverse sides 31 of each of the transducers may overlap the corners cof the adjacent transducer, and thus cover the space a existing betweenthe transducers. In this way, the tables will be subjected to vibrationwaves across their entire area. If such diagonal arrangement werenotprovided for, the space a between the respective transducers which isnecessary for proper vibratory action, would allow narrow strips on thesurface of the tables or sheets thereon to go untouched resulting in aninadequately cleaned surface.

When all of the transducers 11 are properly supported along the channels20 and 21, the whole bank of trans ducers may be vertically adjusted toplace the transducer working surfaces or faces 32 at the desired heightabove the surface to be cleaned by means of opposed adjustment screws33, held in place by lock nut34, and carried by the horizontal flangeportions 17 of the cross beam 12. These adjustment screws engage theclamping brackets 19 and provide a means whereby the brackets may beraised or lowered in the slot 18 defined by the flanges 16 and 17, andthus cause the channels 20 and 21 to raise or lower the transducers 11to place them in proper position with respect to the surface of thetables 10 or sheets carried thereby. The clamping brackets 19 are keptin aligned position with respect to the vertical flanges 16 by means ofkeys 35 mounted on the inside of the flange which engage key-ways 36formed in the sides of the clamping brackets. Thus, when the bracketsare moved upwardly and downwardly the keys 35 engage the ways 36 andallow the brackets and channels associated therewith to move only in avertical direction.

In accordance with this phase of the invention, as noted hereinbefore, asupply of liquid energy transmitting medium is maintained between theworking surfaces 32 of the transducers and the surface being cleaned sothat a cavitation effect can be set up in the liquid medium which willcause the molecular structure of the foreign material on the surface tobe disturbed. This energy transmitting medium may be supplied by meansof pipes or conduits 37 (Fig. 2) mounted above the path of the tablesand adjacent the lower working faces 32 of the transducers 11. Moreparticularly, the liquid medium, designated by the numeral 38 (Fig. 2),is directed onto the surface of the tables 10 and beneath the said faces32 by means of spray holes 39 provided along the length of the pipes orconduits 37. In this manner, it is possible to set up and maintain afilm of fluid over a narrow area of the surface being cleaned. Whilethis film or layer of energy conducting liquid is extremely thin andvertically unconfined, it nevertheless completely fills the spacebetween the transducer working faces 32 and the table surface due, atleast to someextent, to surface tension and capillary attraction. Theseeffects act to maintain the energy conducting medium beneath thetransducer faces at a level substantially higher than that of theunconfined film'of the liquid that flows away from the transducers ontothe remaining portion of the table surface. It will therefore be evidentthat the liquid medium 38, although unconfined, may be maintained in athin but effective layer over the necessary narrow width of surfacebeing cleaned, thus eliminating the need for tanks or other confiningmeans to contain the liquid in sufficient volume to cover the transducergenerating faces. The advantages of a technique in which the energytransmitting liquid is spread in a thin unconfined layer over a narrowarea of the surface being cleaned, over prior known ultrasonic cleaningapplications requiring large volumes of energy conducting medium incumbersome rc taining tanks to completely surround the transducer or thearticle being cleaned will be apparent.

In operation the distance between the transducer working faces 32 andthe table or objects being cleaned can be varied by means of theadjustment described hereinbefore, and the distance providedtherebetween related to the surface tension and capillary attractioncharacteristics of the energy transmitting liquid. For example, withliquids having the greater surface tension and capillary attractioncharacteristics the transducers can be maintained at a greater vdistance from the surface being cleaned inasmuch as the surface tensionwill not be overcome as easily to permit the liquid to become separatedfrom the working faces 32.

With the transducer position determined, the conducting medium 38 isdeposited therebeneath upon and over a narrow width of the table 10being cleaned where it will substantially fill the narrow space betweenthe transducer generating faces 32 and the table surfaces and bemaintained by the natural forces mentioned above. The transducers arethen energized by an alternating voltage supplied to the coils 26thereof causing extremely rapid vibrations to occur along the area ofthe working faces 32. Since the generating surfaces are in directcontact with the liquid medium 38, alternate positive and negativepressure fronts which travel directly from the vibrating surfaces orfaces to the surface being cleaned along a path normal thereto arecreated. These variable pressure fronts cause a cavitation or bubbleeffect to take place in the medium which in turn acts upon the moleculesof foreign material appearing on the surface being cleaned by firstcompressing the molecules toward the surface, and then pulling themolecules toward the vibration generating elements as the bubblescollapse and create a negative pressure area.

As the tables 10 move past the bank of transducers 11, the surfacesthereof are cleaned as they are swept by the cleaning action of thecavitation effect mentioned above. This movement of the tables 10 pastthe working faces 32 of the transducers also causes a slight build up ofthe energy conducting medium along the side of the transducers facingthe uncleaned portion of the table because of the .damming effect of thetransducers and the resistance to flow of the medium and adhering to thetransducer in the restricted opening between the table surface and thesaid working faces. Such damming effect aids the surface tension andcapillary attractioncharacteristics of the medium by providing anabundant supply of liquid medium in contact with the working'surfaces 32at all times when the tables are moving therepast.

While an energy transmitting medium of water may be advantageously usedin many cases, in others, it is desirable to use a detergent medium as atransmitting medium as noted above. Forexample, in using a detergentmedium, when the molecules are subjected to negative pressures they arespread from one another in minute degrees allowing the liquid medium toseep into the interstices and form a wetting layer between the adjacentmolecules. Eventually the detergent action of the liquid medium betweenthe molecules causes the molecules to separate from each other and fromthe sheet thusleaving the sheet free of foreign matter. These alternate.positive and negative pressure fronts may be set up'from 100 to 30,000times per second, resulting in tremendous pressures-on the molecularstructure of the depositmaterial during a short interval of time.Consequently, the detergent action of the liquid medium on the molecularstructure of the deposit material causes the material to becomesuspended in the liquid in a matter of seconds. In this connection, formany applications it is desirable to use'de-aerated energy transmittingmediums as such ble pressure wave fronts. On the other hand, if thematerial to be cleaned can be dissolved by an acid in cansing a chemicalreaction to take place between the acid and the deposit matter, a mediumof the type might also be used in conjunction with the vibrationgenerators to remove the deposit on the said surfaces. Other types ofmediums may also be employed to obtain the cleansing action regardlessof their chemical nature e.g. kerosene, sodium silicate, as well asliquids containing certain types of abrasive material which cause aneroding action to take place on the foreign matter itself.

As pointed out above, the cleaning method of this in-. vention is basedprimarily on the action of cavitation.

Wehave also discovered that the effectiveness of the cleaning action,particularly in such difficult cleaning functions as the removal ofplaster from grinding and polishing tables, is dependent on themagnitude of displacement at the working face of the transducer. Inother words, we find that displacement magnitudes or amplitudes suitablefor other purposes, and even for other cleaning operations, areinsuflicient to effectively clean hardened plaster from metal surfaces.

To illustrate, trials with-the magnetostrictive transducer shown anddescribedhere-as one form of suitable vibration generator with which theinvention can be practiced disclosed that when normal cleaning power of50 'watts was applied to the transducer it failed to effectively removeplaster. It was our theory that this was due to the fact thateifectiveplaster removal is dependent on the degree of cavitation asdetermined by the amplitude of displacement at the working face of thetransducer or, differently expressed, on a sufficiently high powerdensity, expressed in watts per square inch, at the working face.

By way of confirmation, we found that when we multiplied the power inputsome sixteen times, applying 800 watts that the very effective andcomplete cleaning described above was obtained. However, it should beun- 6 derstood that the matter of applied power is probably not thecontrolling factor because it is expected that the advent of vibrationgenerators of greater efficiency, which may be of the same or differenttypes or constructions from the magnetostrictive type here indicated asthe preferred form, sufficient displacement orpower density at theworking face may be obtained with a much lower power input.

While the vibration generators 11 used topro'duce'the cavitationeffectin a liquid medium may operate continuously without interruption,it has been found that they overheat and tend to'lose their efficiencywhen operated continuously for long periods of time. Tocompensate forthis condition, thereis herein provided a coolor other suitable coolingmediums upon the transducers so as to provide a cooling effect thereforand thus allow the transducers to operate at peak efficiency. However,it isto be pointed out that other'types of cooling means may be employedsuch as cooling pipes which cool by heat absorption, or air jets, etc.

Should it be desired to move thecleaning assembly to another table lineor location, the complete unit may be moved without moving theindividual'transducers therefrom by releasing the bolts 15 attaching thebeam to the standards 13 and lifting the supporting beam 12 along theboss 43 extendingalong the upper portion of thebeam by means of cranehooks or the like which may be inserted in holes 44 provided therein.

An alternate embodiment of the invention is shown in Fig. 6 whichdiffers from the embodiment of Figs. lto 5 by providing two parallelrows of vibration generators or transducers 11. This arrangement may beused to clean surfaces which have'an unusually hard material thereonrequiring a greater amount of energy to break down the molecularstructure thereof. Also, thearrangement shown in this embodiment may beused when'it is desired to 'move the conveying'means or tables 10 at agreater speed. If desired, in this embodiment it is not necessary thatthe transducers 11 and support 12 be disposed at an angle to the path ofmovement of the tables 10 since the respective transducersmaybestaggered to overlap one another as shown in Fig. 6.

It will be apparent that while the cleaning'apparatus discl'osedhereinhas been described in connection with cleaning of plaster from movingtables that it may also be used 'to clean sheet material'such as steelplate or glass and that the transducers may be moved while the objectbeing cleaned remains substantially stationary or moves relativethereto.

It is also 'to be understood that the form of the invention disclosedherein is tobe taken as the preferred embodiment thereof, and thatvarious changes in the shape, size and arrangement of parts may beresorted to without departing from the spirit of the invention or thescope of the following claims.

We claim:

1. Apparatus for cleaning a moving'surface comprising, a support mountedabovethe path of said moving "surface, a plurality of vibrationgenerating elements provrded with'working faces and mounted on saidsupport in a position to provide vibrations substantially normal to thesurface being'cleaned, and means for building up a layer of an energytransmitting liquid on a localized area of said surface that fills allof the space between the entire working faces said vibration generatingelements and of said localized area as said surface moves past saidvibration generating elements.

2. Apparatus for cleaning moving flat surfaced objects comprising meansfor moving said objects along a definite path, a plurality of vibrationgenerating elements mounted above said path and in overlappingrelationship transversely thereof, 'sald vibration generating'elementshaving vibrating surfaces substantially parallel to the plane of saidpath for providing vibrations substantially normal to the surface beingcleaned and means for maintaining a layer of energy transmitting liquidbetween and in contact with said elements and said objects.

3. Apparatus for cleaning a moving flat surfaced objcct comprising,means for moving said object along a definite path, magneto-strictivetransducers mounted above and diagonally of said path of said movingobject, said magneto-strictive transducers having vibratory facessubstantially in a common plane and relatively close to the surfacebeing cleaned, and means for depositing an energy transmitting liquid ona localized area of said surface and filling all of the space betweenthe entire vibratory faces of said transducers and said localized areaas said object passes beneath said magneto-strictive transducers. j

4. Apparatus for cleaning plaster from a surface of a plate glasssurfacing table comprising, a support mounted above said surfacingtable, a vibration generating element carried by said-support forproviding vibrations substantially normal to the surface being cleaned,means for depositing an energy transmitting liquid between saidvibration generating elements and said surface, and means for adjustingthe vibration generating elements relative to said table andsufiiciently close to said surface to provide a heavy concentration ofenergy at the surface being cleaned and close enough to retain a liquidbetween and in contact with said generating elements and said surface bycapillary action.

5. Apparatus for cleaning plaster from a surface of a plate glasssurfacing table as it moves along a definite path comprising, a supportmounted above said surfacing table, a plurality of magneto-strictivetransducers mounted on said support for providing vibrationssubstantially normal to the surface being cleaned, cooling means forsaid magneto-strictive transducers, means for adjustably moving saidmagneto-strictive transducers relative to said table and sufiicientlyclose to said surface to provide a heavy concentration of energy at thesurface being cleaned and close enough to retain a liquid between and incontact with said magneto-strictive transducers and said surface bycapillary action, and means for depositing an energy conducting liquidbetween said magneto-strictive transducers and said surface, said energyconducting liquid serving to transmit undamped elastic vibrations tosaid surface from said magneto-strictive transducers so as to disturbthemolecular structure of end and side portions at an angle to the path ofmovement of said moving object, and means adjacent said vibrationgenerating elements for depositing an energy conducting liquid betweenand in contact with said vibration generating elements and said surfaceand which fills all of the space between the entire working face of.each of said elements and said surface in advance of the vibrationgenerating elements.

7. A method of cleaning a surface of a body comprising the steps ofmoving the said body along a predetermined path, providing a thin film'of an energy conducting medium in the form of a tie-aerated liquidhaving a detergent material dissolved therein on a localized area ofsaid body, and conducting elastic vibrations to said surface throughsaid film.

8. In a method of continuously cleaning the entire area of a surface asit moves along a definite path the steps of arranging a plurality offixed position vibration generating elements with their Working surfacesin closely spaced face to face relation with the moving sur face to becleaned and with certain of said elements positioned rearwardly of otherof said elements to bridge the gap between adjacent elements, andmaintaining a relatively thin film of an energy conducting liquidbetween and in contact with said elements and the surface to be cleaned.

9. In a method of cleaning plaster from a surface the steps ofdepositing an unconfined body of an energy conducting liquid on alocalized area of said surface, and transmitting elastic vibrations tosaid energy conducting medium to produce a cavitation effect thereininvolving suflicient displacement to remove the plaster from the surfacethrough said liquid.

10. Apparatus for treating surfaces comprising a support mountedadjacent said surfaces when in position to be treated, a plurality ofvibration generating elements provided with working faces and mounted onsaid support in a position to provide vibrations substantially normal tothe surfaces being treated, means for creating relative movement betweensaid surfaces and said vibration generating elements, and means formaintaining an unconfined layer of an energy transmitting liquid on alocalized area of said surfaces that fills all of the space between theentire working faces of each of said vibration generating elements andsaid localized area during said relative movement therebetween.

11. In a method of treating an area of a surface with a vibrationgenerating element provided with a working face, the steps of creatingrelative movement between the area of said surface to be treated and theworking face of said vibration generating element to cause one to passthe other in close substantially parallel face-toface relation,maintaining a thin unconfined layer of an energy conducting liquidbetween and in contact with said surface area and said working face whenin such relation that fills all of the space between the entire workingface of said vibration generating element and said surface area, andtransmitting vibrations in a direction normal to said surface area fromsaid working face to said thin unconfined layer to produce a cavitationeffect during said relative movement.

References Cited in the file of this patent UNITED STATES PATENTS-2,460,919 Bodine Feb. 8, 1949 2,484,014 Peterson Oct. 11, 19492,651,148 Carwile Sept. 8, 1953 2,702,260 Massa Feb. 15, 1955 2,717,319Bundy, Sept. 6, 1955 FOREIGN PATENTS 278,905 Switzerland Feb. 16, 1952587,214 Great Britain Apr. 17, 1947 978,290 France Nov. 22, 1950 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO, 2,883,310April 21, 1959 James W, McAuley et alfl It is hereby certified thaterror appears in the-printed specification of the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 4, line 75, before "adhering" strike out w and column 6, line;69, after faces" insert of line 70, after and" strike out H fH I Signedand sealed this 18th day of August 1959.,

Attest:

ROBERT C. WATSON KARL AXLINE Commissioner of Patents Attesting OfficerUNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION April 21, 1959Patent No, 2,883,310

James W, McAuley et all,

It is hereby certified that error appears in the-printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

g" strike out and column 6,

Column 4, line '75, 'before adherin line 69, after "faces insert w ofline 70, after and" strike out n fn Signed and sealed this 18th day ofAugust 1959 (SEAL)- Attest:

KARL AXLINE Attesting Ofiicer ROBERT C. WATSON Commissioner of Patents

1. APPARATUS FOR CLEANING A MOVING SURFACE COMPRISING, A SUPPORT MOUNTEDABOVE THE PATH OF SAID MOVING SURFACE, A PLURALITY OF VIBRATIONSSUBSTANTIALLY NORMAL VIDED WITH WORKING FACES AND MOUNTED ON SAIDSUPPORT IN A POSITION TO PROVIDE VIBRATIONS SUBSTANTIALLY NORMAL TO THESURFACE BEING CLEANED, AND MEANS FOR BUILDING UP TO THE SURFACE BEINGCLEANED, AND MEANS FOR BUILDING UP A LAYER OF AN ENERGY TRANSMITTINGLIQUID ON A LOCALIZED AREA OF SAID SURFACE THAT FILLS ALL OF THE SPACEBETWEEN THE ENTIRE WORKING FACES SAID VIBRATION GENERATING ELEMENTS ANDOF SAID LOCALIZED AREA AS SAID SURFACE MOVES PAST SAID VIBRATIONGENERATING ELEMENTS.
 9. IN A METHOD OF CLEANING PLASTER FROM A SURFACETHE STEPS OF DEPOSITING AN UNCONFINED BODY OF AN ENERGY CONDUCTINGLIQUID ON A LOCALIZED AREA OF SAID SURFACE, AND TRANSMITTING ELASTICVIBRATIONS TO SAID ENERGY CONDUCTING MEDIUM TO PRODUCE A CAVITATIONEFFECT THEREIN INVOLVING SUFFICIENT DISPLACEMENT TO REMOVE THE PLASTERFROM THE SURFACE THROUGH SAID LIQUID.